Magnetoresistive behaviour of La-0.67(Ca0.33-xPbx)MnO3 nanopowders prepared at lower temperatures

摘要

We have been able to prepare ultrafine powders of pure and doped La0.67Ca0.33MnO3 (LCMO) at a relatively lower temperature of 550 degreesC using a simple, cost effective and versatile PVA-based chemical route. A maximum magnetoresistance (NIR) ratio of -25% is obtained at 20 K in a magnetic field of 3 kOe. Magnetoresistive behaviour being retained in the nanopowders may have implications for enhancing data storage capacity. The semicondutor-to-metal transition temperature, T-p, however, shifts towards the lower temperature as the particle size is reduced. To improve T-P and near-room-temperature NM additives like NH,NO, and citric acid have been used. In addition, Pb is substituted for Ca. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 15]